@Michael:
Well, Corona is used for mobile 2D Games. Sometimes if we want to port our games/apps to Windows/Mac as well then we use Löve2D. It uses LUA so we can easily make it work with this engine, too.
For 2.5D, 3D games we are currently working with Unity3D. There may be better 3D engines out there like CryEngine but our developers feel more familiar with Unity
The current project is far away from being finished so I can not provide you with further information unfortunately 
Hopefully I am able to participate in the next Graphics 2.0 test… I would like to use Corona for 2.5D games, too.
But our current mobile game made with Corona SDK is in Alpha stage and will be announced very soon…
I did not find a better 2D engine than Corona that fits my needs (ease of use, lightweight etc).
And just a quick note: I´ve started with Corona and my projects have given me a job in a very big German game company 
Max